Final answer:
The Dnieper River flows through Russia and Ukraine, entering from Russia and exiting from Ukraine.
Step-by-step explanation:
The Dnieper River flows through Russia and Ukraine. It enters Russia from its source in the Valdai Hills and then flows south through Belarus before entering Ukraine. It continues to flow through Ukraine and eventually exits the country to the Black Sea. The Dnieper River has played a significant role in the history and development of both Russia and Ukraine.